The specific embodiment
In order to make the object of the invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with specific embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.
The cleaning catalyst for tail gases of automobiles that the embodiment of the invention provides; With the cordierite honeycomb ceramic is carrier; With activated alumina and hydrogen-storing material is coating, is catalyst activity component with precious metal palladium, rhodium, and coating is a double-decker; Wherein ground floor loads on the carrier, contains activated alumina and hydrogen-storing material; The second layer loads on the ground floor coating, contains activated alumina, contains or do not contain hydrogen-storing material.Precious metal palladium, rhodium active component are carried on respectively on the material different, wherein the metal of rhodium and/or oxide carried on the hydrogen-storing material of ground floor, on the metal and/or oxide carried activated alumina at the second layer of palladium.
Described mode of loading is the common mode of loading of those skilled in the art; The noble metal mode of loading has coprecipitation, sol-gel process, infusion process etc.; The coating mode of loading has coating, impregnating; Adopt the mode of dipping that noble metal is loaded on the coating among the present invention, coating is coated on the carrier.
Said coating is selected from the mixture of the molecular sieve of hexa-aluminate and perovskite composite oxide, cerium zirconium sosoloid, rare earth oxide and aluminium oxide, alkaline-earth oxide and high silica alumina ratio.
Said hydrogen-storing material comprises cerium oxide and zirconic mixture, cerium oxide or cerium zirconium sosoloid.The oxide that can also contain La, Pr, Nd, Y, Al in the said hydrogen-storing material.
The soluble-salt of palladium can be a kind of in palladium bichloride, palladium nitrate, palladium, the dichloro diamino palladium among the present invention, and the soluble-salt of rhodium can be a kind of in rhodium nitrate, radium chloride, the chlorine rhodate.
In the catalyst provided by the present invention, the weight ratio of palladium and rhodium is 1-30: 1.
In the catalyst provided by the present invention, with the volume total of catalyst, the total content of coating is 80-350g/L, and wherein the content of palladium is 0.3-5g/L, and the content of rhodium is 0.03-0.5g/L.
In the catalyst provided by the present invention, be benchmark with the stratum total that is coated with of ground floor, wherein the content of activated alumina is 20-90wt%, and the hydrogen-storing material of load rhodium accounts for 10-80wt%, and wherein the content of rhodium is the 0.06-1wt% of hydrogen-storing material; The stratum total that is coated with the second layer is a benchmark, and wherein the content of the activated alumina of supported palladium is 60-100wt%, and hydrogen-storing material accounts for 0-40wt%, and wherein the content of palladium is the 0.3-5wt% of activated alumina.
The above-mentioned Preparation of catalysts method that the embodiment of the invention provides comprises the steps:
(1) the soluble-salt solution with rhodium is carried in the hydrogen-storing material with the mode of flooding, and drying and roasting makes rhodium modification hydrogen-storing material;
(2) the soluble-salt solution with palladium is carried in the activated alumina with the mode of flooding, and drying and roasting makes the palladium modified aluminas;
(3) with the rhodium modification hydrogen-storing material that makes, palladium modified aluminas respectively with water, binding agent mixing and ball milling to 1-10 μ m, process ground floor, second layer coating paste;
(4) said ground floor, second layer coating paste are coated on the catalyst carrier successively, dry, roasting obtain said catalyst.
Among the preparation method provided by the present invention, said drying steps all carries out under 85-130 ℃, is 3-20h drying time.Said drying is a various drying means known in those skilled in the art, comprises microwave drying, infra-red drying, and purpose is that the active presoma with load is converted into active component.The temperature of roasting can not be too high, the time can not be oversize, avoids the aging or oxide carrier sintering of active component.In the present technique scheme, sintering temperature is 450-700 ℃, and roasting time is 1-6h.
Among the preparation method provided by the present invention, the soluble-salt of said palladium can be a kind of in palladium bichloride, palladium nitrate, palladium, the dichloro diamino palladium, and the soluble-salt of rhodium can be a kind of in rhodium nitrate, radium chloride, the chlorine rhodate.In this embodiment, activated alumina all adopts gama-alumina.
Binding agent comprises a kind of in boehmite, aluminium colloidal sol or the Ludox in the above-mentioned steps (3).
Among the preparation method provided by the present invention, also comprise: add nitrate at the said carrier coating slurry that contains aluminium oxide and mix; The content of said nitrate is the 1-5wt% that is coated with stratum total, and said nitrate is one or more in cerous nitrate, zirconium nitrate, lanthanum nitrate, nickel nitrate and the barium nitrate.
Below specify cleaning catalyst for tail gases of automobiles of the present invention and preparation method thereof through embodiment 1-5.
The raw material that adopts is and is purchased in the present embodiment.Hydrogen-storing material adopts cerium zirconium sosoloid (Zibo Huaqing Powder Material Techn Co., Ltd.), and activated alumina adopts gama-alumina (Shandong Zibo rel chemical industry Co., Ltd).
Embodiment 1
Present embodiment is used to explain cleaning catalyst for tail gases of automobiles provided by the invention and preparation method thereof.
With the rhodium chloride solution impregnation 60g cerium zirconium sosoloid of rhodium-containing 0.15g, this cerium zirconium sosoloid by weight, Ce: Zr=4 wherein: 6, through 100 ℃ of dry 6h, 600 ℃ of roasting 2h, make rhodium modification hydrogen-storing material then; Palladium bichloride hydrochloric acid solution dipping 100g activated alumina with containing palladium 1.2g makes the palladium modified aluminas through 100 ℃ of dry 6h, 600 ℃ of roasting 2h then.With rhodium modification hydrogen-storing material 60g, activated alumina 80g, boehmite 20g and water 200g mixing and ball milling to 3 μ m, process the undercoating slurry; With palladium modified aluminas 100g, hydrogen-storing material 30g, boehmite 30g and water 180g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply earlier the undercoating slurry, behind 100 ℃ of dry 6h, 600 ℃ of roasting 2h, on catalyst carrier, apply the external coating slurry again,, make catalyst 1 through 110 ℃ of dry 5h, 600 ℃ of roasting 3h.
Embodiment 2
Present embodiment is used to explain cleaning catalyst for tail gases of automobiles provided by the invention and preparation method thereof.
Rhodium chloride solution impregnation 80g cerium zirconium sosoloid with rhodium-containing 0.2g contains La in this cerium zirconium sosoloid, by weight, and Ce: Zr: La=3 wherein: 6: 1, through 110 ℃ of dry 4h, 550 ℃ of roasting 4h, make rhodium modification hydrogen-storing material then; Palladium bichloride hydrochloric acid solution dipping 120g activated alumina with containing palladium 2g makes the palladium modified aluminas through 110 ℃ of dry 4h, 550 ℃ of roasting 4h then.With rhodium modification hydrogen-storing material 80g, activated alumina 80g, boehmite 20g, barium nitrate 10g and water 220g mixing and ball milling to 3 μ m, process the undercoating slurry; With palladium modified aluminas 120g, hydrogen-storing material 30g, boehmite 30g, barium nitrate 10g and water 240g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply earlier the undercoating slurry, behind 110 ℃ of dry 5h, 600 ℃ of roasting 3h, on catalyst carrier, apply the external coating slurry again,, make catalyst 2 through 110 ℃ of dry 5h, 600 ℃ of roasting 3h.
Embodiment 3
Present embodiment is used to explain cleaning catalyst for tail gases of automobiles provided by the invention and preparation method thereof.
Rhodium chloride solution impregnation 100g cerium zirconium sosoloid with rhodium-containing 0.22g contains Y in this cerium zirconium sosoloid, by weight, and Ce: Zr: Y=3 wherein: 6: 0.5, through 90 ℃ of dry 10h, 550 ℃ of roasting 4h, make rhodium modification hydrogen-storing material then; Palladium bichloride hydrochloric acid solution dipping 150g activated alumina with containing palladium 1.5g makes the palladium modified aluminas through 90 ℃ of dry 10h, 550 ℃ of roasting 4h then.With rhodium modification hydrogen-storing material 100g, activated alumina 60g, boehmite 20g and water 200g mixing and ball milling to 3 μ m, process the undercoating slurry; With palladium modified aluminas 150g, boehmite 30g, nickel nitrate 20g and water 220g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply earlier the undercoating slurry, behind 90 ℃ of dry 10h, 550 ℃ of roasting 4h, on catalyst carrier, apply the external coating slurry again,, make catalyst 3 through 100 ℃ of dry 5h, 600 ℃ of roasting 3h.
Embodiment 4
Present embodiment is used to explain cleaning catalyst for tail gases of automobiles provided by the invention and preparation method thereof.
With the rhodium nitrate solution of rhodium-containing 0.08g dipping 40g cerium zirconium sosoloid, contain Pr in this cerium zirconium sosoloid, by weight, Ce: Zr: Pr=3 wherein: 6: 0.5, through 110 ℃ of dry 5h, 600 ℃ of roasting 2h, make rhodium modification hydrogen-storing material then; Palladium nitrate solution dipping 80g activated alumina with containing palladium 1.3g makes the palladium modified aluminas through 110 ℃ of dry 5h, 600 ℃ of roasting 2h then.With rhodium modification hydrogen-storing material 40g, activated alumina 30g, boehmite 10g, barium nitrate 5g, with water 120g mixing and ball milling to 3 μ m, process the undercoating slurry; With palladium modified aluminas 80g, boehmite 10g, barium nitrate 5g and water 130g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply earlier the undercoating slurry, behind 110 ℃ of dry 5h, 600 ℃ of roasting 3h, on catalyst carrier, apply the external coating slurry again,, make catalyst 4 through 110 ℃ of dry 6h, 600 ℃ of roasting 4h.
Embodiment 5
Present embodiment is used to explain cleaning catalyst for tail gases of automobiles provided by the invention and preparation method thereof.
With the rhodium nitrate solution of rhodium-containing 0.25g dipping 60g cerium zirconium sosoloid, contain Al in this cerium zirconium sosoloid, by weight, Ce: Zr: Al=6 wherein: 3: 1, through 90 ℃ of dry 10h, 550 ℃ of roasting 4h, make rhodium modification hydrogen-storing material then; Palladium nitrate solution dipping 120g activated alumina with containing palladium 1.3g makes the palladium modified aluminas through 90 ℃ of dry 10h, 550 ℃ of roasting 4h then.With rhodium modification hydrogen-storing material 60g, activated alumina 100g, 10% aluminium colloidal sol 100g, barium nitrate 5g, with water 120g mixing and ball milling to 3 μ m, process the undercoating slurry; With palladium modified aluminas 120g, 10% aluminium colloidal sol 100g, zirconium nitrate 20g and water 80g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply earlier the undercoating slurry, behind 90 ℃ of dry 10h, 550 ℃ of roasting 4h, on catalyst carrier, apply the external coating slurry again,, make catalyst 5 through 90 ℃ of dry 10h, 600 ℃ of roasting 4h.
Comparative Examples 1
Rhodium chloride solution impregnation 60g cerium zirconium sosoloid with rhodium-containing 0.15g contains La in this cerium zirconium sosoloid, by weight, and Ce: Zr: La=3 wherein: 6: 1, through 100 ℃ of dry 6h, 600 ℃ of roasting 2h, make rhodium modification hydrogen-storing material then; Palladium bichloride hydrochloric acid solution dipping 60g activated alumina with containing palladium 1.2g makes the palladium modified aluminas through 100 ℃ of dry 6h, 600 ℃ of roasting 2h then.With rhodium modification hydrogen-storing material 60g, activated alumina 80g, boehmite 20g and water 200g mixing and ball milling to 3 μ m, process the undercoating slurry; With palladium modified aluminas 60g, hydrogen-storing material 70g, boehmite 30g and water 180g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply earlier the undercoating slurry, behind 100 ℃ of dry 6h, 600 ℃ of roasting 2h, on catalyst carrier, apply the external coating slurry again,, make comparative catalyst 1 through 110 ℃ of dry 5h, 600 ℃ of roasting 3h.
Comparative Examples 2
Rhodium chloride solution impregnation 80g activated alumina with rhodium-containing 0.2g through 110 ℃ of dry 4h, 550 ℃ of roasting 4h, makes the rhodium modified aluminas then; Palladium bichloride hydrochloric acid solution dipping 120g activated alumina with containing palladium 2g makes the palladium modified aluminas through 110 ℃ of dry 4h, 550 ℃ of roasting 4h then.With rhodium modified active aluminium oxide 80g, cerium zirconium sosoloid 80g, contain Pr in this cerium zirconium sosoloid, by weight, Ce: Zr: Pr=3 wherein: 6: 0.5, boehmite 20g, barium nitrate 10g and water 220g mixing and ball milling to 3 μ m processed the undercoating slurry; With palladium modified aluminas 120g, hydrogen-storing material 30g, boehmite 30g, barium nitrate 10g and water 240g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply earlier the undercoating slurry, behind 110 ℃ of dry 5h, 600 ℃ of roasting 3h, on catalyst carrier, apply the external coating slurry again,, make comparative catalyst 2 through 110 ℃ of dry 5h, 600 ℃ of roasting 3h.
Comparative Examples 3
Palladium bichloride hydrochloric acid solution dipping 150g activated alumina with containing palladium 1.5g makes the palladium modified aluminas through 90 ℃ of dry 10h, 550 ℃ of roasting 4h then; Rhodium chloride solution impregnation 100g cerium zirconium sosoloid with rhodium-containing 0.22g contains Y in this cerium zirconium sosoloid, by weight, and Ce: Zr: Y=3 wherein: 6: 0.5, through 90 ℃ of dry 10h, 550 ℃ of roasting 4h, make rhodium modification hydrogen-storing material then.With palladium modified aluminas 150g, boehmite 30g, nickel nitrate 20g and water 220g mixing and ball milling to 3 μ m, process the undercoating slurry; With rhodium modification hydrogen-storing material 100g, activated alumina 60g, boehmite 20g and water 200g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply earlier the undercoating slurry, behind 90 ℃ of dry 10h, 550 ℃ of roasting 4h, on catalyst carrier, apply the external coating slurry again,, make comparative catalyst 3 through 100 ℃ of dry 5h, 600 ℃ of roasting 3h.
Comparative Examples 4
With the rhodium nitrate solution of rhodium-containing 0.24g dipping 120g cerium zirconium sosoloid, contain Pr in this cerium zirconium sosoloid, by weight, Ce: Zr: Pr=3 wherein: 6: 0.5, through 110 ℃ of dry 5h, 600 ℃ of roasting 2h, make rhodium modification hydrogen-storing material then; Palladium nitrate solution dipping 120g activated alumina with containing palladium 2g makes the palladium modified aluminas through 110 ℃ of dry 5h, 600 ℃ of roasting 2h then.With rhodium modification hydrogen-storing material 120g, palladium modified aluminas 120g, boehmite 40g, barium nitrate 20g, with water 360g mixing and ball milling to 3 μ m, process coating paste.On Φ 80 * 60mm catalyst carrier, apply the two layers of coatings slurry,, make comparative catalyst 4 through 110 ℃ of dry 6h, 600 ℃ of roasting 4h.
Comparative Examples 5
With the rhodium nitrate solution of rhodium-containing 0.2g dipping 60g cerium zirconium sosoloid, contain Al in this cerium zirconium sosoloid, by weight, Ce: Zr: Al=6 wherein: 3: 1, through 90 ℃ of dry 10h, 550 ℃ of roasting 4h, make rhodium modification hydrogen-storing material then; Platinum nitrate solution dipping 80g activated alumina with platiniferous 1.2g makes the platinum modified aluminas through 90 ℃ of dry 10h, 550 ℃ of roasting 4h then.With rhodium modification hydrogen-storing material 60g, activated alumina 100g, 10% aluminium colloidal sol 100g, barium nitrate 5g, with water 120g mixing and ball milling to 3 μ m, process the undercoating slurry; With platinum modified aluminas 80g, hydrogen-storing material 40g, 10% aluminium colloidal sol 100g, barium nitrate 10g and water 80g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply earlier the undercoating slurry, behind 90 ℃ of dry 10h, 550 ℃ of roasting 4h, on catalyst carrier, apply the external coating slurry again,, make comparative catalyst 5 through 90 ℃ of dry 10h, 600 ℃ of roasting 4h.
Comparative Examples 6
With activated alumina 80g, hydrogen-storing material 80g, boehmite 20g, barium nitrate 10 and water 220g mixing and ball milling to 3 μ m, process the undercoating slurry; With activated alumina 120g, hydrogen-storing material 30g, boehmite 30g, barium nitrate 10g and water 240g mixing and ball milling to 3 μ m, process the external coating slurry.On Φ 80 * 60mm catalyst carrier, apply the undercoating slurry earlier; Behind 110 ℃ of dry 5h, 600 ℃ of roasting 3h; In the 200g of rhodium-containing 0.28g rhodium chloride solution, flood 10-30min,, on catalyst carrier, apply the external coating slurry again through 110 ℃ of dry 4h, 600 ℃ of roasting 2h; Behind 110 ℃ of dry 5h, 600 ℃ of roasting 3h; In containing the 200g palladium bichloride hydrochloric acid solution solution of palladium 1.4g, flood 10-30min,, make comparative catalyst 6 through 110 ℃ of dry 4h, 600 ℃ of roasting 2h.
Performance test
1, the HC ignition active testing of the aging front and back of embodiment and Comparative Examples
Adopt following method, respectively to the not aged catalyst sample among embodiment 1-5 and the Comparative Examples 1-6 and aging after the light off characteristics of catalyst sample estimate, HC compound initiation temperature data are seen table 1.
Catalyst carrier is put into quartz tube reactor, pass through quartz ampoule, the HC compound concentration of process catalyst carrier when writing down different temperatures simultaneously, HC conversion of compounds rate when calculating different temperatures with simulated exhaust gas.HC initiation temperature (T
50) reach 50% o'clock reaction temperature for HC conversion of compounds rate.Aging condition is to contain higher SO under 1000 ℃
2Calcine 10h in the simulated exhaust gas of concentration, aging consisting of: NO 1000ppm, SO with simulated exhaust gas
220ppm, CO 1.5%, C
3H
81000ppm, CO
210%, H
2O 10%, O
25%, N
2Be balance gas.
The condition of test initiation temperature: air speed is 6 * 10
4h
-1, probe temperature is from 160 ℃ to 400 ℃, and the temperature interval is 20 ℃, and simulated exhaust gas consists of CO 1.06%, C
3H
80.11%, NO0.098%, CO
210.0%, O
21.03%, N
2Be balance gas.
Table 1 HC compound initiation temperature
2,400 ℃ of catalytic activitys tests of the aging front and back of embodiment and Comparative Examples
The catalyst sample that respectively the fresh catalyst sample among embodiment and the comparative example is reached after wearing out is 400 ℃ in the simulated exhaust gas temperature, and air speed is 5 * 10
4h
-1Estimate under the condition, conversion data is seen table 2.Concrete method of testing and aging condition are all the same.
The condition of test initiation temperature: air speed is 6 * 10
4h
-1, probe temperature is 400 ℃, simulated exhaust gas consists of CO 1.06%, C
3H
80.11%, NO 0.098%, CO
210.0%, O
21.03%, N
2Be balance gas.
Table 2 catalyst is to the conversion ratio of each composition in the tail gas
Can find out that referring to table 1 and table 2 the catalyst HC ignition activity that the embodiment of the invention provides is good, behind sulfur-bearing atmosphere high temperature ageing, HC ignition activity and catalytic activity thereof all reduce less, explain that its low temperature ignition activity is good, and ageing-resistant performance is good.The HC initiation temperature of the fresh sample of Comparative Examples 1-6, though the catalyst that provides with the embodiment of the invention be more or less the same because in the catalyst of Comparative Examples 1; Palladium coating hydrogen-storing material too high levels; The catalyst rhodium of Comparative Examples 2 loads on the activated alumina, and palladium is distributed in internal layer in the catalyst of Comparative Examples 3, and rhodium is distributed in skin; The palladium catalyst of Comparative Examples 4, rhodium mixed distribution are at same one deck; The palladium catalyst of Comparative Examples 6, rhodium are immersed on the blank coating, through sulfur-bearing atmosphere aging after, the active all obviously decline of catalytic conversion efficiency during with 400 ℃ of the catalyst HC ignition of above-mentioned Comparative Examples; Its ignition activity, resistant to thermal aging or sulfur poisoning-resistant ability are described, especially to the obvious variation of the changing effect of HC and NO.In addition; The test result of comparing embodiment 1-5 palladium-rhodium and Comparative Examples 5 platinum-rhodium catalyst can be found out, palladium-rhodium catalyst that present embodiment provides can reach the same effect of platinum-rhodium catalyst fully; Thereby can really apply in the cleaning catalyst for tail gases of automobiles; Reduce the catalyst cost, can guarantee that again its ignition activity is good, ageing-resistant performance is good simultaneously, satisfy the low emission requirement.
The above is merely preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of within spirit of the present invention and principle, being done, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.